反应详情

温度

70 °C

32a from Example 5 (5 g, 15.97 mmol) is suspended in absolute ethanol (50 ml) and heated to 70° C. O-Ethyl hydroxylamine hydrochloride (2.4 g, 24.61 mmol) is added and the mixture is heated to reflux for 1.5 hours. After cooling the solvent is removed by evaporation, and the residue is stirred with aqueous sodium hydroxide (50 ml, 1 M). The crude product is filtered off. Column-chromatographic workup on silica gel using a mixture of ethyl acetate and ethanol (9:1) as the eluent affords pure 33a. Yield: 3.7 g (65%). Mp 105-106° C.

1. temperaturethe mixture is heated
2. temperatureto reflux for 1.5 hours
3. temperatureAfter cooling the solvent
4. customis removed by evaporation
5. filtrationThe crude product is filtered off
6. additionColumn-chromatographic workup on silica gel using a mixture of ethyl acetate and ethanol (9:1) as the eluent